A traditional cell in a wireless telecommunications system might cover a relatively large geographical area. To enhance the coverage of such a macro cell, one or more smaller scale cells might be located in or near the macro cell and might provide a wireless device with a more reliable connection than might be available with the macro cell alone. For example, if a small-scale cell is created inside a house, wireless devices in the house might connect to a macro cell through the small-scale cell and might receive a better quality of service than if they connected directly to the macro cell. These small-scale cells are known by various names, such as microcells, picocells, femtocells, hot zone cells, relay cells, and the like.
Access to a small-scale cell might be restricted to only certain authorized users, who can be referred to as a closed subscriber group or CSG. For example, members of a family who live in a house covered by a small-scale cell might make up a CSG. Hereinafter, these small-scale cells will be referred to as CSG cells. In some cases, multiple CSG cells might be available to a single CSG. For example, a company with several buildings in a single campus might maintain a CSG cell in each of the buildings, and employees who are authorized to access the CSG cells would comprise a CSG.
A small-scale cell might allow access to both its authorized users, i.e., users that subscribe to the CSG to which the small-scale cell belongs, and unauthorized users, i.e., users that do not subscribe to the CSG to which the small-scale cell belongs. This type of small-scale cell is called a hybrid cell. The authorized users may be provided preferential services in a hybrid cell over the unauthorized users.
The embodiments described herein are applicable to CSG cells, hybrid cells, and other types of small-scale cells, as well as macro cells that have limited resources. As used herein, the term “CSG cell” refers to any such cell.
The physical equipment and software that create a CSG cell can function analogously to a base station, a node B, or an enhanced node B (eNB) in a traditional cell and might called a home node B, a home eNB (HeNB), or a similar name. Hereinafter, this equipment and software will be referred to as a HeNB, but it should be understood that a HeNB is not necessarily used only in a home and is not necessarily an eNB.
Devices, systems, and/or software that can connect to a HeNB may include mobile phones, mobile wireless devices (including digital, cellular, or dual mode devices), personal digital assistants, laptop/tablet/notebook computers, desktop computers, or any other end user device or system that can connect to a wireless telecommunications network. Hereinafter, such a device, system, and/or software will be referred to as user equipment or UE.